In the related art, in an image forming apparatus such as a scanner, a copying machine, or a multi-function peripheral (MFP), an image of a document is formed on an image sensor by imaging the document using an illumination device and a lens array in which plural lenses are arranged to direct the image of the document to the image sensor. In addition, in an image forming apparatus such as a printer, a copying machine, or a multi-function peripheral (MFP), by using a light emitting element such as an LED and a lens array, light rays emitted from the LED are imaged on a photoconductor drum through the lens array, and the image is formed (exposed) on the photoconductor drum. The lens array is formed, for example, by combining plural lenses and apertures.
However, in such a lens array, when optical axes deviate from each other between lenses through which one light ray passes, imaging characteristics greatly deteriorate and non-uniformity in light intensity at the focal plane becomes severe. In addition, when plural lenses and apertures are combined, a deviation during assembly causes deterioration in performance.
JP-A-2002-62407 discloses an imaging element array in which imaging elements are combined to avoid deterioration in performance caused by a misalignment of multiple lenses during assembly of an imaging apparatus. However, since there are two reflective surfaces at a position where a light flux width is wide, the positional accuracy of the reflective surfaces effects image formation. Therefore, there is a problem in that it is necessary to increase the time needed to mold the lens in a molding operation.